I guess the main confusion of defining this lens is probably the setting of depth/frequency. >AIkkQT
diN5*CF'~
The main fresnel lens types are: F<y$Q0Z}
GGHe{l
* Constant groove depth. JJlwzH
* Contant groove pitch types. Ftu~nh}
KZ^W@*`D
So if your depth is fixed you will define +ve value in the cell and to specify the "height" or "depth" of each groove feature. If the frequency of the groove is fixed then you use -ve value. Say putting down - 5 this implies that there are 5 grooves with a unit length. WF#eqU*&
8;>vgD
Hope this helps!!